Recently, our laboratory has developed techniques for establishing primary cultures from rat ventral prostate (RVP) using collagenase digestion and selective attachment procedures. We propose to use this method to establish primary cultures of prostatic epithelial cells derived from canine and rat prostate, and to determine the appropiate medium, serum, hormone and growth factor combination that will permit prolonged growth and survival of prostatic epithelial cells derived from both species. These primary cultures will be characterized to determine that they retain the following properties of normal prostatic epithelium: 1) Karyology and chromosome banding, 2) A non-transformed contact inhibited state, 3) The ability to bind sex steroids (androgen and estrogen), 4) The ability to metabolize testosterone to predominantly 5 alpha-reduced 17 beta-hydroxy-steroid metabolites, 5) The ability to produce and secrete acid phosphatase, 6) Maintain an epithelial appearance when examined by light and electron microscopy. In addition, the effects of sex-steroids on: 1) androgen metabolism, 2) acid phosphatase production and, 3) the formation of secretory granules and intracellular junction, in prostatic epithelial cells grown in primary culture will be investigated. These well characterized epithelial cultures can then be used in future studies to investigate early functional changes prior to the onset of adenocarcinoma.